This invention relates to an infrared intrusion sensor. In particular, the invention relates to an infrared intrusion sensor which is a long range passive detection system designed for remote unattended surveillance applications. The invention is expected to find applications in airfield perimeter security, high grade fence line security, vital asset protection and other surveillance environments.
The sensor differs from other infrared intrusion sensors in that it has a superior detection range compared to existing devices. Furthermore it provides more extensive information to the operator. For example, the invention has the capability of indicating the direction of movement of a target, number of targets, false alarm probability, near/far field indication, and failure/tamper indication.
In one existing device designed for military use the useable range is 30 metres although the optimum detection range is stated to be 6 metres. This device is admitted to have difficulties with slow-moving targets between 15 metres and 30 metres. In another military device the stated detection ranges are 3 to 20 metres for personnel and 3 to 50 metres for vehicles.
Domestic intrusion sensors have a typical detection range of less than 20 metres. One known civilian security sensor has a detection range of 100 meters but only provides a simple alarm.
These existing intrusion sensors have technical limitations, the major limitation being the relatively short range capabilities of these devices and unacceptably high false alarm rates. Most existing sensors are not capable of indicating the direction of target movement, or if they can indicate the direction of movement it is at the expense of other facilities.
It is an object of this invention to provide an infrared intrusion sensor having enhanced detection range and low false alarm rate compared to existing devices.
It is a further object of this invention to alleviate one or more of the above mentioned problems or at least provide the public with a useful alternative.